The present invention relates to non-woven webs and, more particularly, to antimicrobially active, air-laid, non-woven webs, to wet wipers containing such a web, and to a method of making the web.
Wet wiper products, including those utilizing nonwoven and air laid webs, require antimicrobial properties to destroy or inhibit the growth of various microorganisms, bacteria, yeasts, and molds. Typically, the antimicrobial agent or agents are incorporated in the liquid or lotion phase of the wet wiper product. In this manner, the antimicrobial agent is able to penetrate throughout the entire wiper product and, thus, provide a sort of homogeneous antimicrobial efficacy.
The nonwoven webs used in wet wiper products also usually contain a polymeric binder and a catalyst to aid in the crosslinking of the binder to develop sufficient wet strength in the web. Unfortunately, when the product is ultimately used, the catalysts can leach out into the lotion phase of the wiper and thereby rub-off, thus leaving an irritating residue on the skin of the user. Many individuals exhibit adverse reactions to such residues and, hence, their enjoyable use of the nonwoven web and wet wiper product is significantly impeded.
Although organic acids have been used in nonwoven webs to catalyze the cross-linking of the binders present in the nonwoven webs, the art has failed to recognize that these chemicals can be selected not only to act as a binder catalyst, but also to possess antimicrobial properties. For example, U.S. Pat. No. 3,922,462 to Katz uses oxalic, dichloroacetic, and paratoluenesulfonic acids to catalyze a binder in a web. These acids, however, are toxic upon ingestion or inhalation, as well as being a skin irritant. Hence, when these acids leach from the web, instead of providing a beneficial effect, they pose significant health and safety hazards.
Thus, these wiper products require an antimicrobial agent, in addition to the catalyst and binder, to impart antimicrobial properties to the web. The need for a separate antimicrobial agent adds time and cost to the process of making the product. For example, when an antimicrobial agent is presently added to the non-woven web in an off-line process after the non-woven web product has been formed, the cost of producing the wet wiper product is increased.
In sum, present wet wiper products that exhibit antimicrobial activity are less than satisfactory. Often, the webs contain binder catalysts that are toxic and leave an irritating residue on the user's skin. If these undesirable properties are avoided by removing the catalyst after the binder cure but before the web is used, time and cost are added to the process of making the web.